Specification of the design snow loads for gable roofs based on a consistent probabilistic approach

基于一致概率方法的山墙屋顶设计雪荷载规范

• 批准号: 99264718
• 负责人: Privatdozent Dr.-Ing. Michael Kasperski
• 金额: --
• 依托单位: Forschungsteam EKIB - Entwurfsgrundlagen im Konstruktiven Ingenieurbau
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/99264718?language=en
• 关键词: Specification; design; snow; loads; gable

One of the basic tasks of codification in regard to climatologic actions is the area-wide specification of the design values based on observations for single stations. The statistical stability of the estimated values greatly depends on the ensemble size. This is true for the estimates of each single station as well as for the geostatistical interpolation, i.e. the more observations are sampled for the single station ensembles and the more stations are used as input for the geostatistical interpolaten the higher is the statistical stability of the results. For 224 stations in Germany, extreme value statistics can be performed directly based on the observed water equivalents, which are available on average for 37 years. The developed probabilistically equivalent snow density model in combination with the new approach of using independent events instead of yearly extremes leads to considerable larger ensemble sizes with 130 entries on average. The translation of the single station model to regional models allows analysing a further 525 stations which provide only observations of the height of the snow cover. A further improvement, i.e. a reduction of the statistical uncertainties, is obtained by introducing super-stations which combine observations from single stations following a consistent probabilistic strategy. Then, the type of distribution can be identified with a sufficient statistical stability. Aim of the project is the utilization of the observed snow height data in the scope of the extreme value statistics of the snow loads and the statistical optimal specification of the corresponding design values. This requires a consistent strategy for the detection of outliers in terms of very rare events. The actual strategy used in the European snow load research is less appropriate, since too many events are not detected and a large number of events are erroneously classified as outlier. Aim of the project is the development and application of an improved strategy, which especially considers unbiased estimators like BLUE. Thus, it becomes possible to analyse true outliers in a probabilistic consistent way. The accumulation and spatial distribution of snow on roofs greatly depends on the wind speed. The snow-wind climate of Germany can be sub-divided into three basic types. Type I shows for large snow loads virtually deterministic wind speed values. Then, the shape parameters can be specified on the load model which has been developed in the first period of the project. Type II features scattering wind speeds, which requires extensions of the basic convolution integrals. Only for type III storm and snow occur simultaneously. Then, consistent combination rules are required for these two climatologic actions.

关于气候作用的编纂的基本任务之一是基于单个站点的观察值的设计值的区域规范。估计值的统计稳定性在很大程度上取决于整体大小。对于每个单个站点以及地统计插值的估计值，即对单个站组合物进行采样的观察值越多，并且使用越多的站点被用作地列置互座的输入，越高的是结果的统计稳定性。对于德国的224个站，可以直接基于观察到的水等效物直接执行极端价值统计数据，这平均可用37年。开发的概率等效的雪密度模型结合使用独立事件而不是每年极端的新方法，导致相当大的合奏尺寸，平均为130个条目。单个站模型向区域模型的翻译允许分析另外的525个站，这些站点仅提供对积雪高度的观察。通过引入一致的概率策略结合了单个站点的观测值，可以获得进一步的改进，即减少统计不确定性。然后，可以以足够的统计稳定性来识别分布的类型。该项目的目的是利用雪载的极端值统计范围和相应设计值的统计最佳规范的利用。这需要一致的策略来检测异常值，从而在非常罕见的事件中。欧洲雪负荷研究中使用的实际策略不太合适，因为未检测到太多事件，并且大量事件被错误地归类为离群值。该项目的目的是开发和应用改进的策略，该战略尤其考虑了诸如蓝色之类的公正估计量。因此，有可能以概率一致的方式分析真实异常值。屋顶上的雪的积聚和空间分布在很大程度上取决于风速。德国的雪风气候可以分为三种基本类型。 I型显示大雪负荷实际上是确定性的风速值。然后，可以在项目第一阶段开发的负载模型上指定形状参数。 II型具有散射风速，需要扩展基本的卷积积分。仅适用于III型风暴和降雪同时发生。然后，这两种气候行动需要一致的组合规则。